China's Xi draws 'red line' in Hong Kong as protesters march

China’s President Xi Jinping warned on Saturday that any challenge to Beijing’s control over Hong Kong crossed a “red line”, as thousands calling for more democracy marched through the city 20 years since it was handed back by Britain. Xi spoke in a televised address after swearing in new Hong Kong leader Carrie Lam, who is already being cast by critics as a China stooge in a city where many are angry at Beijing’s tightening grip on the freedoms of its nearly eight million people. A huge security operation shut down large parts of Hong Kong for Xi’s three-day visit, reflecting Beijing’s concern that there should be no embarrassment ahead of a key Communist Party congress later this year which is expected to cement his position as the most powerful Chinese leader in a generation.